CN110002476B

CN110002476B - Preparation method of lithium hydroxide

Info

Publication number: CN110002476B
Application number: CN201910293912.5A
Authority: CN
Inventors: 王怀有; 王敏; 赵有璟; 李锦丽
Original assignee: Qinghai Institute of Salt Lakes Research of CAS
Current assignee: Qinghai Institute of Salt Lakes Research of CAS
Priority date: 2019-04-12
Filing date: 2019-04-12
Publication date: 2021-05-25
Anticipated expiration: 2039-04-12
Also published as: US11267719B2; US20220041460A1; CN110002476A; WO2020207223A1

Abstract

The invention discloses a preparation method of lithium hydroxide, which comprises the following steps: A. coprecipitating the lithium extraction mother liquor of the salt lake brine by using an aluminum salt solution and a sodium hydroxide solution, performing solid-liquid separation after aging, washing and drying to obtain lithium aluminum hydrotalcite; B. acidifying the lithium aluminum hydrotalcite to obtain a lithium aluminum acid solution; C. carrying out nanofiltration aluminum lithium separation and reverse osmosis primary concentration on the lithium aluminum acid solution in sequence to obtain a primary concentrated lithium-rich solution; D. deeply removing aluminum from the lithium-rich solution to obtain aluminum-removed lithium-rich solution; E. carrying out bipolar membrane electrodialysis on the aluminum-removed lithium-enriched liquid to obtain a secondary concentrated lithium-enriched liquid; F. and evaporating and concentrating the secondary concentrated lithium-rich liquid to obtain the lithium hydroxide. The preparation method comprises the steps of firstly preparing lithium aluminum hydrotalcite by using lithium carbonate-containing salt lake brine lithium extraction mother liquor as a raw material, transferring lithium ions into an aqueous solution by an acidification method, separating the lithium ions from impurity ions, removing aluminum, and performing bipolar membrane electrodialysis concentration to obtain lithium hydroxide, so that lithium resources are fully utilized, and the resource utilization rate is improved.

Description

Preparation method of lithium hydroxide

Technical Field

The invention belongs to the technical field of comprehensive utilization of salt lake resources, and particularly relates to a preparation method of lithium hydroxide.

Background

Lithium is the lightest metal element in the nature, is silvery white, has unique physicochemical characteristics such as high specific heat, high conductivity and strong chemical activity, and has wide application. At present, the application of metallic lithium and its compounds in the traditional industrial fields of glass ceramics, electrolytic aluminum, lubricating grease, air-conditioning refrigeration and organic synthesis, metallurgy, chemical engineering, medicine, reagents and the like is continuously increased, and the application in the fields of energy sources such as aluminum-lithium alloy, lithium battery and nuclear fusion, the military industry, aerospace, nuclear industry and the like is also rapidly expanded, so the metallic lithium and its compounds are known as 'industrial monosodium glutamate', and are also regarded as important strategic materials by many countries; and is praised as energy metal promoting the world progress due to the application of the lithium battery. In nature, lithium resources are mainly present in solid ores and liquid brines. The important position of brine lithium resources in the development of lithium resources in the world is established for nearly 30 years, and the brine lithium resources have attracted the attention of lithium resource development industries in the aspects of application and extraction of lithium compounds. The international trend of lithium salt production is mainly to extract lithium from salt lakes and assisted by the extraction of lithium by an ore method; in China, lithium extraction from salt lake brine has the advantages of large resource quantity, low cost and the like, and along with the increasing exhaustion of solid lithium ore resources, the salt lake brine gradually becomes a main source of lithium resources.

At present, the mainstream process for the lithium extraction technology of the salt lake with high magnesium-lithium ratio mainly comprises the following steps: salt field process, magnesium-lithium separation, impurity removal of lithium-containing solution, precipitation and conversion of lithium carbonate and the like; the lithium carbonate precipitation conversion is to add a sodium carbonate solution into a lithium-rich solution, prepare lithium carbonate through a precipitation reaction, and simultaneously generate a lithium carbonate mother solution after solid-liquid separation, namely a lithium extraction mother solution of salt lake brine, wherein the lithium content in the lithium carbonate mother solution can still reach 1 g/L-2 g/L, and the lithium carbonate mother solution is an important lithium resource and is to be recycled.

For the lithium carbonate mother liquor, the existing process for recycling the lithium carbonate mother liquor generally comprises the steps of firstly removing carbonate in the lithium carbonate mother liquor by hydrochloric acid, and then adding alkali to adjust the pH value of the lithium carbonate mother liquor; therefore, the first process is complex, the second process needs acid and alkali consumption, the cost is high, carbonate in the second process is not reasonably utilized, and resources are wasted. Therefore, it is necessary to search for a completely new method for recovering and recycling the lithium carbonate mother liquor.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation method of lithium hydroxide, which prepares lithium hydroxide by taking lithium extracted mother liquor from salt lake brine containing lithium carbonate as a raw material, fully utilizes lithium resources in the lithium hydroxide and improves the utilization efficiency of the resources.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

a preparation method of lithium hydroxide comprises the following steps:

s1, simultaneously dripping an aluminum salt solution and a sodium hydroxide solution into the lithium extraction mother liquor of the salt lake brine, carrying out coprecipitation reaction on the three solutions at 25-70 ℃, and keeping the pH of the system at 8-13 to obtain a nucleation system with lithium aluminum hydrotalcite crystal nuclei; wherein, in the lithium extraction mother liquor of the salt lake brine, Li⁺Has a concentration of 1g/L to 2g/L, CO₃ ^2-Has a concentration of 10g/L to 30g/L, OH^-The concentration of (A) is 5 g/L-25 g/L;

s2, aging the nucleation system at 50-150 ℃ for 6-48 h, and then carrying out solid-liquid separation to obtain a lithium aluminum hydrotalcite filter cake;

s3, washing and drying the lithium aluminum hydrotalcite filter cake to obtain lithium aluminum hydrotalcite;

s4, dissolving the lithium aluminum hydrotalcite by using 2-12 mol/L hydrochloric acid as a raw material and adopting an acidification method to obtain a lithium aluminum acid solution; wherein, in the lithium aluminate solution, Li⁺Has a concentration of 1.5g/L to 10g/L, Al³⁺Has a concentration of 10g/L to 80g/L and Cl^-The concentration of (A) is 70 g/L-450 g/L;

s5, sequentially carrying out aluminum-lithium separation and primary enrichment concentration on the lithium-aluminum acid solution in a nanofiltration system and a reverse osmosis system to obtain primary concentrated lithium-rich solution; wherein, in the nanofiltration freshwater obtained after nanofiltration, Li⁺The concentration of the aluminum-lithium composite material is 0.2 g/L-2.0 g/L, and the aluminum-lithium ratio is 0.01-0.6; in the primary concentrated lithium-rich liquid obtained after reverse osmosis, Li⁺The concentration of the aluminum-lithium composite material is 1.5 g/L-8.0 g/L, and the aluminum-lithium ratio is 0.01-0.6;

s6, deeply removing aluminum from the primary concentrated lithium-rich solution to obtain an aluminum-removed lithium-rich solution; wherein, in the aluminum-removing lithium-rich liquid, Li⁺Has a concentration of 1.5g/L to 8g/L, Al³⁺Is not more than 100 ppm;

s7, performing secondary enrichment concentration on the aluminum-removed lithium-rich liquid in a bipolar membrane electrodialysis system to obtain a secondary concentrated lithium-rich liquid; wherein, in the secondary concentrated lithium-rich liquid, Li⁺Has a concentration of 3g/L to 30g/L and Na⁺The concentration of (A) is 0.04 g/L-12 g/L;

and S8, carrying out evaporation concentration on the secondary concentrated lithium-rich liquid under vacuum or inert gas protection to obtain lithium hydroxide.

Further, in the step S1, Al in the aluminum salt solution³⁺And Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the substances is 1:1 to 5: 1; OH in the sodium hydroxide solution^-And OH in the lithium extraction mother liquor of the salt lake brine^-The sum of the amount of the substances and Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the substance(s) is 4:1 to 10: 1.

Further, in the step S1, Al in the aluminum salt solution³⁺And Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the substances is 1.5:1 to 3.5: 1; OH in the sodium hydroxide solution^-And OH in the lithium extraction mother liquor of the salt lake brine^-The amount of the substances is equal to the amount of Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the substances (A) is 5:1 to 8: 1.

Further, in the step S1, the pH value of the system is kept to be 9-11 in the coprecipitation reaction process.

Further, in the step S1, the salt lake brine lithium extraction mother liquor and the aluminum salt solution and the sodium hydroxide solution are subjected to a co-precipitation reaction at 30-50 ℃.

Further, in the salt lake brine lithium extraction mother liquor, Li⁺The concentration of (A) is 1.3g/L to 1.7g/L, CO₃ ^2-Has a concentration of 15g/L to 25g/L, OH^-The concentration of (A) is 10 g/L-20 g/L; in the lithium-containing solution, Li⁺The concentration of the aluminum-lithium composite material is 0.5 g/L-1.5 g/L, and the aluminum-lithium ratio is 0.05-0.3; in the primary concentrated lithium-rich liquid, Li⁺The concentration of the aluminum-lithium composite material is 3.5 g/L-7.5 g/L, and the aluminum-lithium ratio is 0.05-0.3; in the secondary concentrated lithium-rich liquid, Li⁺Has a concentration of 1.5g/L to 8g/L, Al³⁺Is not more than 10 ppm.

Further, the aluminum salt solution is any one of an aluminum nitrate solution, an aluminum sulfate solution, or an aluminum chloride solution.

Further, in the step S5, Li is obtained after the first concentration and enrichment⁺The concentration of the water is 0.005 g/L-0.1 g/L; the desalted produced water is used for preparing the aluminum salt solution.

Further, in the step S2, the nucleation system is aged by a hydrothermal method or a reflux method.

Further, in the step S1, the aluminum salt solution and the sodium hydroxide solution are both added dropwise to the lithium extraction mother liquor of the salt lake brine at a rate of 1mL/min to 5 mL/min.

Further, in the step S7, electroosmosis is performed by passing through the bipolar membraneLi in initial lithium hydroxide solution in precipitation system⁺The concentration is 0.06 g/L-0.7 g/L, Na in the initial polar liquid⁺The concentration is 6.5 g/L-15 g/L; the circulation time is 10min to 30min, and the bipolar membrane electrodialysis voltage is 10V to 30V.

The method comprises the steps of taking a salt lake brine lithium extraction mother liquor as a raw material, adopting a coprecipitation method to separate and extract lithium resources, converting lithium, carbonate and hydroxyl into lithium aluminum hydrotalcite, and then transferring lithium ions in the obtained lithium aluminum hydrotalcite into an aqueous solution again through an acidification method, so that the lithium ions are separated from impurity ions such as carbonate, and the process of removing carbonate by adopting an acid-base adjustment method in the prior art is avoided, wherein the lithium aluminum acid solution obtained after acidification is subjected to nanofiltration-reverse osmosis-deep aluminum removal-bipolar membrane electrodialysis in sequence, and finally lithium hydroxide is prepared; the purity of the obtained lithium hydroxide can reach 99.0%. The preparation method combines comprehensive utilization and functional utilization of salt lake resources, and improves the utilization efficiency of the resources.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. This invention may, however, be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and its practical application to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.

The invention provides another brand-new recycling method of the lithium extraction mother liquor from the salt lake brine, aiming at the problems of resource waste, complex process, high cost caused by acid and alkali consumption and the like of the conventional general treatment method of the lithium extraction mother liquor from the salt lake brine.

Specifically, the preparation method of the lithium hydroxide comprises the following steps:

in step S1, an aluminum salt solution and a sodium hydroxide solution are simultaneously added dropwise into the lithium extraction mother liquor of the salt lake brine, the three solutions are subjected to coprecipitation reaction at 25-70 ℃ and preferably 30-50 ℃, and the pH of the system is kept at 8-13 and preferably 9-11, so that the nucleation system with lithium-aluminum hydrotalcite crystal nuclei is obtained.

Specifically, the salt lake brine lithium extraction mother liquor used as the raw material basically comprises the following components: li⁺Has a concentration of 1g/L to 2g/L, preferably 1.3g/L to 1.7g/L, CO₃ ^2-Has a concentration of 10g/L to 30g/L, preferably 15g/L to 25g/L, OH^-The concentration of (B) is 5 to 25g/L, preferably 10 to 20 g/L.

More specifically, the aluminum salt solution is any one of an aluminum nitrate solution, an aluminum sulfate solution, or an aluminum chloride solution.

Further, Al in the aluminum salt solution is controlled³⁺And Li in the lithium extraction mother liquor of salt lake brine⁺The amount ratio of the substances (A) is 1:1 to 5:1, preferably 1.5:1 to 3.5: 1; at the same time, OH in the sodium hydroxide solution is controlled^-And OH in the lithium extraction mother liquor of salt lake brine^-The sum of the amount of the substances and Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the component (A) to the component (B) is 4:1 to 10:1, preferably 5:1 to 8: 1.

Preferably, an aluminum salt solution and a sodium hydroxide solution with the same volume as the lithium extraction mother liquor of the salt lake brine are prepared in advance, and Al in the aluminum salt solution is controlled³⁺The mass concentration of the substance is Li in the lithium extraction mother liquor of the salt lake brine⁺The amount concentration of the substance (C) is 1 to 5 times, preferably 1.5 to 3.5 times, and OH in the sodium hydroxide solution is controlled^-And OH in the lithium extraction mother liquor of salt lake brine^-The sum of the quantities of the substances is Li in the lithium extraction mother liquor of the salt lake brine⁺The amount concentration of the substance (C) is 4 to 10 times, preferably 5 to 8 times. Then, preferably, the aluminum salt solution and the sodium hydroxide solution are both dripped into the lithium extraction mother liquor of the salt lake brine at the speed of 1-5 mL/min to carry out coprecipitation reaction of the aluminum salt solution and the sodium hydroxide solution.

Therefore, the pre-prepared lithium aluminum hydrotalcite nucleation process is completed through the coprecipitation reaction between the salt lake brine lithium extraction mother liquor and the aluminum salt solution and the sodium hydroxide solution which are added simultaneously, and the formed lithium aluminum hydrotalcite crystal nucleus can be used as the basis for the subsequent growth of the lithium aluminum hydrotalcite.

In step S2, the nucleation system is aged for 6 h-48 h at 50-150 ℃ and then subjected to solid-liquid separation to obtain the lithium aluminum hydrotalcite filter cake.

The above-mentioned aging can be carried out by a hydrothermal method or a reflux method.

In step S3, the lithium aluminum hydrotalcite filter cake is washed and dried to obtain lithium aluminum hydrotalcite.

Preferably, the washed lithium aluminum hydrotalcite filter cake is dried for 12 to 48 hours at the temperature of between 60 and 120 ℃ to obtain the lithium aluminum hydrotalcite.

In step S4, the lithium aluminum hydrotalcite is dissolved by an acidification method to obtain a lithium aluminum acid solution.

Specifically, in the obtained lithium aluminate solution, Li⁺Has a concentration of 1.5g/L to 10g/L, Al³⁺Has a concentration of 10g/L to 80g/L and Cl^-The concentration of (A) is 70g/L to 450 g/L.

In step S5, the lithium-aluminum acid solution is sequentially subjected to aluminum-lithium separation and primary enrichment concentration in the nanofiltration system and the reverse osmosis system to obtain a primary concentrated lithium-rich solution.

Specifically, the lithium aluminate solution is subjected to nanofiltration separation operation in a nanofiltration system to obtain Li in the solution⁺The concentration of the nanofiltration fresh water is 0.2-2.0 g/L, preferably 0.5-1.5 g/L, and the aluminum-lithium ratio is 0.01-0.6, preferably 0.05-0.3; the nanofiltration fresh water is subjected to reverse osmosis primary concentration operation in a reverse osmosis system to obtain Li⁺The concentration of (a) is 1.5-8 g/L, preferably 3.5-7.5 g/L, and the ratio of aluminum to lithium is 0.01-0.6, preferably 0.05-0.3.

Preferably, the lithium aluminate solution is diluted by 4-15 times, preferably 7-12 times, and then subjected to aluminum lithium separation nanofiltration operation, wherein the nanofiltration membrane ratio is controlled to be 1: 1-7: 1, preferably 2: 1-5: 1, and the operation pressure of the separation unit is 0.5-5.0 MPa, preferably 2.0-4.0 MPa. In the process of carrying out primary enrichment concentration reverse osmosis operation on the nanofiltration fresh water, the proportion of the reverse osmosis membrane is controlled to be 1: 1-7: 1, preferably 2: 1-5: 1, the concentration volume ratio (the volume ratio of the lithium aluminate solution to the primary concentrated lithium-rich solution) is 4: 1-15: 1, preferably 5: 1-11: 1, and the operation pressure of a concentration unit is 1 MPa-10 MPa, preferably 2.5 MPa-6 MPa.

In the step, the nanofiltration membrane used for the aluminum-lithium separation nanofiltration operation can be one or two of a DK membrane, a DL membrane and a NF membrane; and the reverse osmosis membrane used for the primary enrichment concentration reverse osmosis operation may be a dow BW membrane and/or a SW membrane.

The nanofiltration fresh water is subjected to reverse osmosis primary concentration operation, and desalted water corresponding to the primary concentrated lithium-rich liquid phase is obtained; li in the desalted water⁺The concentration of (B) is 0.05g/L to 0.1g/L, and the aluminum salt solution can be prepared.

In step S6, the first concentrated lithium-rich liquid is subjected to deep aluminum removal to obtain an aluminum-removed lithium-rich liquid.

Specifically, in the obtained aluminum-removing lithium-rich solution, Li⁺Has a concentration of 1.5-8.0 g/L, Al³⁺Is not more than 10 ppm.

In step S7, the aluminum-removed lithium-enriched liquid is subjected to secondary enrichment concentration in the bipolar membrane electrodialysis system to obtain a secondary concentrated lithium-enriched liquid.

Specifically, the bipolar membrane electrodialysis system used in this step includes a cathode chamber and an anode chamber which are arranged oppositely, and a membrane stack arranged between the two polar chambers (i.e., the cathode chamber and the anode chamber); the membrane stack consists of a plurality of bipolar membranes which are arranged in parallel. The bipolar membranes are divided into a plurality of alkali chambers and feed liquid chambers which are alternately arranged, and each chamber (namely the alkali chamber and the feed liquid chamber) is provided with a chamber partition plate. The outside of the pole chamber is connected with a pole liquid tank, the outside of the alkali chamber is connected with an alkali liquid tank, and the outside of the feed liquid chamber is connected with a feed liquid tank; initial polar liquid is stored in the polar liquid tank, initial lithium hydroxide liquid is stored in the alkali liquid tank, and partial aluminum-removing lithium-rich liquid is stored in the feed liquid chamber; thus, the aluminum-removing lithium-rich liquid can be circulated between the material liquid tank and the material liquid chamber, the initial lithium hydroxide liquid between the alkali liquid tank and the alkali chamber and the initial polar liquid between the polar liquid tank and the polar chamber through the pump; after the circulation for a certain time, applying direct current with a certain voltage. Catalytic electrolysis of water in DC electric field and bipolar membrane to produce H⁺And OH^-OH under the action of DC electric field^-Into the alkali chamber, and H⁺Then enters the feed liquid chamber; li in the feed compartment⁺And Na⁺Entering an alkali chamber, and under the continuous electrodialysis process, Li⁺And OH^-Enrichment in the base chamber. Finally obtaining secondary concentrated lithium-rich liquid in an alkali chamber; the secondary concentrated lithium-rich liquid contains lithium hydroxide as a main component and a small amount of sodium hydroxide.

Further, controlling Li in the initial lithium hydroxide solution⁺The concentration is 0.06 g/L-0.7 g/L, Na in the initial polar liquid⁺The concentration is 6.5 g/L-15 g/L; the circulation time is 10min to 30min, and the bipolar membrane electrodialysis voltage is 10V to 30V.

Thus, in the obtained secondary concentrated lithium-rich liquid, Li⁺Has a concentration of 3 to 30g/L, preferably 5 to 18g/L, Na⁺The concentration of (B) is 0.04g/L to 12 g/L.

Meanwhile, hydrochloric acid enrichment liquid is also obtained in the feed liquid chamber; in the hydrochloric acid rich solution, H⁺The concentration of (B) is 0.4 to 4.5g/L, preferably 0.7 to 2.6 g/L.

In step S8, the concentrated lithium-rich solution is evaporated, concentrated and crystallized in an MVR system to obtain lithium hydroxide.

Specifically, the evaporation process is vacuum evaporation or evaporation under the protection of inert gas, and the evaporation temperature is controlled to be 50-110 ℃; after evaporation, concentration and crystallization, the crystallization product can be dried at 40-100 ℃, thereby obtaining the lithium hydroxide product.

Thus, the preparation method of the invention can obtain the lithium hydroxide product with the content as high as 99.0%.

Thus, the salt lake brine lithium extraction mother liquor is used as a raw material, a coprecipitation method is adopted to separate and extract lithium resources, carbonate and hydroxyl in the lithium resources are fully utilized, and lithium, carbonate and hydroxyl are converted into lithium aluminum hydrotalcite with wide application; then transferring the lithium resource in the lithium aluminum hydrotalcite to the water phase again by an acid dissolution method, thereby realizing the separation of the lithium resource and other impurity ions, and directly preparing the lithium hydroxide by evaporating, concentrating and enriching the obtained lithium-containing solution. The preparation method combines the comprehensive utilization and the functional utilization of salt lake resources, and improves the utilization efficiency of the resources; the preparation method has the advantages of greenness, high efficiency, energy conservation, low investment, low energy consumption, little pollution and the like, and the process equipment is simple, short in operation flow, easy to control and suitable for industrial popularization.

The above-mentioned method for producing lithium hydroxide of the present invention will be described below by way of specific examples, but the following examples are merely specific examples of the production method of the present invention and are not intended to limit the entirety thereof.

Example 1

In this embodiment, the lithium extraction mother liquor from salt lake brine from a salt lake brine of Qinghai produces a mother liquor after lithium carbonate is prepared; wherein Li⁺Has a concentration of 1.3g/L, CO₃ ^2-Has a concentration of 15g/L, OH^-The concentration of (2) is 5 g/L.

First, 67.8g of aluminum chloride hexahydrate was weighed out to prepare 1L of an aluminum salt solution, and 18.30g of sodium hydroxide was weighed out to prepare 1L of a sodium hydroxide solution.

And then, simultaneously dripping the prepared aluminum salt solution and sodium hydroxide solution into 1L of the salt lake brine lithium extraction mother liquor at the speed of 5mL/min, and carrying out coprecipitation reaction on the three solutions at the temperature of 70 ℃ and the pH value of 11 to obtain a nucleation system with lithium-aluminum hydrotalcite crystal nuclei.

And thirdly, carrying out hydrothermal aging on the obtained nucleation system at 150 ℃ for 48h, and then filtering to obtain the lithium aluminum hydrotalcite filter cake.

Fourthly, washing the lithium aluminum hydrotalcite filter cake to be nearly neutral, and drying for 48 hours at 120 ℃ to obtain the lithium aluminum hydrotalcite.

Fifthly, completely dissolving the obtained lithium aluminum hydrotalcite in 2mol/L hydrochloric acid solution to obtain lithium aluminum acid solution, wherein Li⁺Has a concentration of 1.5g/L, Al³⁺Concentration 10g/L, Cl^-The concentration was 70 g/L.

Sixthly, diluting the lithium aluminum acid solution by 2 times, and then feeding the solution into a DK nanofiltration system for aluminum lithium separation and nanofiltration operation, and controlling the operation pressure to be 2.0MPa to obtain Li⁺The nanofiltration fresh water with the concentration of 0.5g/L, Al/Li mass ratio of 0.3; then the nanofiltration fresh water is fed intoPerforming primary concentration in BW series reverse osmosis system, controlling the membrane-entering pressure to be 2.5MPa and the concentration volume ratio (lithium-rich solution volume/primary concentrated solution) to be 5.0, and obtaining Li⁺The reverse osmosis concentrated water with the concentration of 3.5g/L and the aluminum-lithium ratio of 0.3; then the reverse osmosis concentrated water enters an electrodialysis system for secondary concentration to obtain Li⁺The concentration of (3) was 22.0g/L, and the aluminum-lithium ratio was 0.5.

In the meantime, obtained is Li⁺The reverse osmosis fresh water with the content of 0.10g/L is directly reused for diluting the lithium aluminate solution.

And seventhly, adding a sodium hydroxide solution with the mass fraction of 30% into the concentrated lithium-rich liquid to remove aluminum ions of the concentrated lithium-rich liquid until the concentration of the aluminum ions is not more than 10ppm, and then carrying out solid-liquid separation to obtain the aluminum-removed lithium-rich liquid.

And step eight, introducing the aluminum-removed lithium-rich liquid into a bipolar membrane electrodialysis system for secondary enrichment and concentration to obtain secondary concentrated lithium-rich liquid.

In particular, Li to be obtained⁺Adding the first-time concentrated lithium-rich liquid with the concentration of 3.5g/L into a feed liquid tank, and adding Li into an alkali liquid tank⁺Adding Na into initial lithium hydroxide solution with concentration of 0.3g/L in a polar liquid tank⁺Respectively enabling a primary concentrated lithium-rich liquid to circulate between a material liquid tank and a material liquid chamber, an initial lithium hydroxide liquid to circulate between an alkali liquid tank and an alkali chamber and a polar liquid to circulate between the polar liquid tank and two polar chambers through a material liquid pump, an alkali liquid pump and a polar liquid pump, setting the bipolar membrane electrodialysis voltage to be 30V to carry out bipolar membrane electrodialysis after 10min of circulation, obtaining a hydrochloric acid-rich liquid in the material liquid tank after the bipolar membrane electrodialysis, and simultaneously obtaining Li in the alkali liquid tank⁺The concentration is 20g/L, Na⁺Secondary concentration lithium-rich liquid with concentration of 12g/L to obtain H in hydrochloric acid-rich liquid⁺The concentration was 2.6 g/L.

Finally, evaporating and concentrating the concentrated lithium-rich liquid in an MVR system under vacuum at the temperature of 50 ℃, crystallizing, and drying the crystallized product at the temperature of 40 ℃ to obtain the lithium hydroxide.

In the lithium hydroxide obtained in this example, the content of lithium hydroxide monohydrate was as high as 99.0% or more.

Example 2

In this embodiment, the lithium extraction mother liquor from salt lake brine from a salt lake brine of Qinghai produces a mother liquor after lithium carbonate is prepared; wherein Li⁺Has a concentration of 2g/L, CO₃ ^2-Has a concentration of 10g/L, OH^-The concentration of (2) is 20 g/L.

First, 540.4g of aluminum nitrate nonahydrate was weighed out to prepare 1L of an aluminum salt solution, and 10.8g of sodium hydroxide was weighed out to prepare 1L of a sodium hydroxide solution.

And then, simultaneously dripping the prepared aluminum salt solution and sodium hydroxide solution into 1L of the salt lake brine lithium extraction mother liquor at the speed of 1mL/min, and carrying out coprecipitation reaction on the three solutions at the temperature of 50 ℃ and the pH value of 8 to obtain a nucleation system with lithium-aluminum hydrotalcite crystal nuclei.

And thirdly, carrying out hydrothermal aging on the obtained nucleation system at 50 ℃ for 68h, and then filtering to obtain the lithium-aluminum hydrotalcite filter cake.

Fourthly, washing the lithium aluminum hydrotalcite filter cake to be nearly neutral, and drying for 30h at the temperature of 60 ℃ to obtain the lithium aluminum hydrotalcite.

Fifthly, completely dissolving the obtained lithium aluminum hydrotalcite in 12mol/L hydrochloric acid solution to obtain lithium aluminum acid solution, wherein Li⁺Has a concentration of 10g/L, Al³⁺Concentration 80g/L, Cl^-The concentration was 450 g/L.

Sixthly, diluting the lithium aluminum acid solution by 12 times, then feeding the solution into a DL nanofiltration system for aluminum lithium separation and nanofiltration operation, and controlling the operation pressure to be 5.0MPa to obtain Li⁺The nanofiltration fresh water with the concentration of 2g/L, Al/Li mass ratio of 0.01; then the nanofiltration fresh water enters an SW series reverse osmosis system for primary concentration, the membrane inlet pressure is controlled to be 10MPa, and the concentration volume ratio (lithium-rich solution volume/primary concentrated solution) is controlled to be 15, so that Li in the nanofiltration fresh water is obtained⁺The reverse osmosis concentrated water with the concentration of 8g/L and the aluminum-lithium ratio of 0.01; then the reverse osmosis concentrated water enters an electrodialysis system for secondary concentration to obtain Li⁺Is 15g/L, and the aluminum-lithium ratio is 0.05.

In the meantime, obtained is Li⁺Reverse osmosis fresh water with content of 0.01g/L is directly usedAnd recycling the solution for diluting the lithium aluminate solution.

And seventhly, adding a sodium hydroxide solution with the mass fraction of 20% into the concentrated lithium-rich liquid to remove aluminum ions of the concentrated lithium-rich liquid until the concentration of the aluminum ions is not more than 10ppm, and then carrying out solid-liquid separation to obtain the aluminum-removed lithium-rich liquid.

In particular, Li to be obtained⁺Adding the first-time concentrated lithium-rich liquid with the concentration of 1.5g/L into a feed liquid tank, and adding Li into an alkali liquid tank⁺Initial lithium hydroxide solution with concentration of 0.06g/L, Na is added into a polar liquid tank⁺Respectively enabling a primary concentrated lithium-rich liquid to circulate between a material liquid tank and a material liquid chamber, an initial lithium hydroxide liquid to circulate between an alkali liquid tank and an alkali chamber and a polar liquid to circulate between the polar liquid tank and two polar chambers through a material liquid pump, an alkali liquid pump and a polar liquid pump, setting the bipolar membrane electrodialysis voltage to be 10V to carry out bipolar membrane electrodialysis after 30min of circulation, obtaining a hydrochloric acid-rich liquid in the material liquid tank after the bipolar membrane electrodialysis, and simultaneously obtaining Li in the alkali liquid tank⁺The concentration is 3g/L, Na⁺Secondary concentration lithium-rich liquid with concentration of 0.04g/L to obtain H in hydrochloric acid-rich liquid⁺The concentration was 0.4 g/L.

And finally, evaporating, concentrating and crystallizing the concentrated lithium-rich liquid in an MVR system under the protection of inert gas at the temperature of 110 ℃, and drying the crystallized product at the temperature of 100 ℃ to obtain the lithium hydroxide.

Example 3

In this embodiment, the lithium extraction mother liquor from salt lake brine from a salt lake brine of Qinghai produces a mother liquor after lithium carbonate is prepared; wherein Li⁺Has a concentration of 1.7g/L, CO₃ ^2-Has a concentration of 30g/L, OH^-The concentration of (2) is 25 g/L.

First, 146.7g of aluminum sulfate was weighed out to prepare 1L of aluminum salt solution, and 19.8g of sodium hydroxide was weighed out to prepare 1L of sodium hydroxide solution.

And then, simultaneously dripping the prepared aluminum salt solution and sodium hydroxide solution into 1L of the salt lake brine lithium extraction mother liquor at the speed of 3mL/min, and carrying out coprecipitation reaction on the three solutions at the temperature of 30 ℃ and the pH value of 13 to obtain a nucleation system with lithium-aluminum hydrotalcite crystal nuclei.

And thirdly, carrying out hydrothermal aging on the obtained nucleation system at 80 ℃ for 24h, and then filtering to obtain the lithium aluminum hydrotalcite filter cake.

And fourthly, washing the lithium aluminum hydrotalcite filter cake to be nearly neutral, and drying for 20 hours at the temperature of 80 ℃ to obtain the lithium aluminum hydrotalcite.

Fifthly, completely dissolving the obtained lithium aluminum hydrotalcite in 6mol/L hydrochloric acid solution to obtain lithium aluminum acid solution, wherein Li⁺Has a concentration of 5g/L, Al³⁺Concentration 40g/L, Cl^-The concentration was 225 g/L.

Sixthly, diluting the lithium aluminum acid solution by 5 times, and then feeding the solution into a NF nanofiltration system to perform aluminum lithium separation and nanofiltration operation, and controlling the operation pressure to be 4.0MPa to obtain Li⁺The nanofiltration fresh water with the concentration of 1.5g/L, Al/Li mass ratio of 0.6; then the nanofiltration fresh water enters a BW series reverse osmosis system for primary concentration, the membrane inlet pressure is controlled to be 6MPa, and the concentration volume ratio (lithium-rich solution volume/primary concentrated solution) is controlled to be 11, so that Li is obtained⁺The reverse osmosis concentrated water with the concentration of 7.5g/L and the aluminum-lithium ratio of 0.6; then the reverse osmosis concentrated water enters an electrodialysis system for secondary concentration to obtain Li⁺The concentration of (2) was 20.0g/L, and the aluminum-lithium ratio was 0.8.

In the meantime, obtained is Li⁺The reverse osmosis fresh water with the content of 0.07g/L is directly reused for diluting the lithium aluminate solution.

And seventhly, adding a sodium hydroxide solution with the mass fraction of 25% into the concentrated lithium-rich liquid to remove aluminum ions of the concentrated lithium-rich liquid until the concentration of the aluminum ions is not more than 10ppm, and then carrying out solid-liquid separation to obtain the aluminum-removed lithium-rich liquid.

Specifically, willObtained Li⁺Adding the first-time concentrated lithium-rich liquid with the concentration of 7.5g/L into a feed liquid tank, and adding Li into an alkali liquid tank⁺Adding Na into initial lithium hydroxide solution with concentration of 0.3g/L in a polar liquid tank⁺Respectively enabling a primary concentrated lithium-rich liquid to circulate between a material liquid tank and a material liquid chamber, an initial lithium hydroxide liquid to circulate between an alkali liquid tank and an alkali chamber and a polar liquid to circulate between the polar liquid tank and two polar chambers through a material liquid pump, an alkali liquid pump and a polar liquid pump, setting the bipolar membrane electrodialysis voltage to be 20V to carry out bipolar membrane electrodialysis after 15min of circulation, obtaining a hydrochloric acid-rich liquid in the material liquid tank after the bipolar membrane electrodialysis, and simultaneously obtaining Li in the alkali liquid tank⁺The concentration is 5g/L, Na⁺Secondary concentration lithium-rich liquid with concentration of 4g/L to obtain H in hydrochloric acid-rich liquid⁺The concentration was 0.7 g/L.

And finally, evaporating, concentrating and crystallizing the concentrated lithium-rich liquid in an MVR system under the protection of inert gas at the temperature of 80 ℃, and drying the crystallized product at the temperature of 60 ℃ to obtain the lithium hydroxide.

Example 4

In this embodiment, the lithium extraction mother liquor from salt lake brine from a salt lake brine of Qinghai produces a mother liquor after lithium carbonate is prepared; wherein Li⁺Has a concentration of 1g/L, CO₃ ^2-Has a concentration of 25g/L, OH^-The concentration of (2) is 10 g/L.

First, 34.791g of aluminum chloride hexahydrate was weighed out to prepare 1L of an aluminum salt solution, and 34.1g of sodium hydroxide was weighed out to prepare 1L of a sodium hydroxide solution.

And then, simultaneously dripping the prepared aluminum salt solution and sodium hydroxide solution into 1L of the salt lake brine lithium extraction mother liquor at the speed of 4mL/min, and carrying out coprecipitation reaction on the three solutions at the temperature of 25 ℃ and the pH value of 9 to obtain a nucleation system with lithium aluminum hydrotalcite crystal nuclei.

And thirdly, carrying out hydrothermal aging on the obtained nucleation system at 100 ℃ for 12h, and then filtering to obtain the lithium aluminum hydrotalcite filter cake.

Fourthly, washing the lithium aluminum hydrotalcite filter cake to be nearly neutral, and drying for 12 hours at the temperature of 100 ℃ to obtain the lithium aluminum hydrotalcite.

Fifthly, completely dissolving the obtained lithium aluminum hydrotalcite in 8mol/L hydrochloric acid solution to obtain lithium aluminum acid solution, wherein Li⁺Has a concentration of 6g/L, Al³⁺Concentration 50g/L, Cl^-The concentration was 280 g/L.

Sixthly, diluting the lithium aluminum acid solution by 15 times, and then feeding the solution into a DK nanofiltration system for aluminum lithium separation and nanofiltration operation, and controlling the operation pressure to be 0.5MPa to obtain Li⁺The nanofiltration fresh water with the concentration of 0.2g/L, Al/Li mass ratio of 0.05; then the nanofiltration fresh water enters an SW series reverse osmosis system for primary concentration, the membrane inlet pressure is controlled to be 1MPa, and the concentration volume ratio (lithium-rich solution volume/primary concentrated solution) is controlled to be 4.0, so that Li in the nanofiltration fresh water is obtained⁺The reverse osmosis concentrated water with the concentration of 1.5g/L and the aluminum-lithium ratio of 0.05; then the reverse osmosis concentrated water enters an electrodialysis system for secondary concentration to obtain Li⁺The concentration of (2) was 13.0g/L, and the aluminum-lithium ratio was 0.06.

And seventhly, adding a sodium hydroxide solution with the mass fraction of 28% into the concentrated lithium-rich liquid to remove aluminum ions of the concentrated lithium-rich liquid until the concentration of the aluminum ions is not more than 10ppm, and then carrying out solid-liquid separation to obtain the aluminum-removed lithium-rich liquid.

In particular, Li to be obtained⁺Adding the primary concentrated lithium-rich liquid with the concentration of 8g/L into a feed liquid tank, and adding Li into an alkali liquid tank⁺Initial lithium hydroxide solution with concentration of 0.5g/L, Na is added into a polar liquid tank⁺Respectively circulating the primary concentrated lithium-rich liquid between a material liquid tank and a material liquid chamber, the initial lithium hydroxide liquid between an alkali liquid tank and an alkali chamber and the polar liquid between the polar liquid tank and the two polar chambers through a material liquid pump, an alkali liquid pump and a polar liquid pump, and setting the bipolar membrane electrodialysis electrodialytic electricity after 20min of circulationPerforming bipolar membrane electrodialysis at a pressure of 15V, obtaining a hydrochloric acid enrichment solution in a feed liquid tank after the bipolar membrane electrodialysis, and obtaining Li in the hydrochloric acid enrichment solution in an alkali liquid tank⁺The concentration is 30g/L, Na⁺Concentrating the lithium-rich solution for the second time with the concentration of 8g/L to obtain H in the hydrochloric acid-rich solution⁺The concentration was 4.5 g/L.

And finally, evaporating, concentrating and crystallizing the concentrated lithium-rich liquid in an MVR system under the protection of inert gas at the temperature of 100 ℃, and drying the crystallized product at the temperature of 80 ℃ to obtain the lithium hydroxide.

While the invention has been shown and described with reference to certain embodiments, those skilled in the art will understand that: various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A preparation method of lithium hydroxide is characterized by comprising the following steps:

wherein Al in the aluminum salt solution³⁺And Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the substances is 1.5:1 to 3.5: 1; OH in the sodium hydroxide solution^-And OH in the lithium extraction mother liquor of the salt lake brine^-The sum of the amount of the substances and Li in the lithium extraction mother liquor of the salt lake brine⁺The amount ratio of the substances is 5:1 to 8: 1;

s2, aging the nucleation system at 50-150 ℃ for 6-48 h by a hydrothermal method or a reflux method, and then carrying out solid-liquid separation to obtain a lithium-aluminum hydrotalcite filter cake;

s6, deeply removing aluminum from the primary concentrated lithium-rich solution to obtain an aluminum-removed lithium-rich solution; wherein, in the aluminum-removing lithium-rich liquid, Li⁺Has a concentration of 1.5-8.0 g/L, Al³⁺Is not more than 10 ppm;

wherein Li in the initial lithium hydroxide solution introduced into the bipolar membrane electrodialysis system⁺The concentration is 0.06 g/L-0.7 g/L, Na in the initial polar liquid⁺The concentration is 6.5 g/L-15 g/L; the circulation time is 10min to 30min, and the bipolar membrane electrodialysis voltage is 10V to 30V;

and S8, putting the concentrated lithium-rich liquid into an MVR system, and carrying out evaporation concentration crystallization under vacuum or inert gas protection to obtain the lithium hydroxide.

2. The preparation method according to claim 1, wherein in the step S1, the pH of the system is maintained at 9-11 during the coprecipitation reaction.

3. The preparation method according to claim 1, wherein in the step S1, the salt lake brine lithium extraction mother liquor and the aluminum salt solution and the sodium hydroxide solution are subjected to a co-precipitation reaction at 30-50 ℃.

4. The preparation method of any one of claims 1 to 3, wherein in the lithium extraction mother liquor of the salt lake brine, Li is contained⁺The concentration of (A) is 1.3g/L to 1.7g/L, CO₃ ^2-Has a concentration of 15g/L to 25g/L, OH^-The concentration of (A) is 10 g/L-20 g/L;

in the nanofiltration freshwater, Li⁺The concentration of the aluminum-lithium composite material is 0.5 g/L-1.5 g/L, and the aluminum-lithium ratio is 0.05-0.3;

in the reverse osmosis concentrate, Li⁺The concentration of the aluminum-lithium composite material is 3.5 g/L-7.5 g/L, and the aluminum-lithium ratio is 0.05-0.3;

in the aluminum-removing lithium-rich liquid, Li⁺Has a concentration of 1.5-8.0 g/L, Al³⁺Is not more than 10 ppm.

5. The production method according to any one of claims 1 to 3, wherein the aluminum salt solution is any one of an aluminum nitrate solution, an aluminum sulfate solution, or an aluminum chloride solution.

6. The method according to claim 5, wherein in the step S5, Li is further obtained after the first concentration and enrichment⁺The concentration of the water is 0.005 g/L-0.1 g/L; the desalted produced water is used for preparing the aluminum salt solution.

7. The preparation method according to any one of claims 1 to 3, wherein in the step S1, the aluminum salt solution and the sodium hydroxide solution are both added dropwise to the lithium extraction mother liquor of the salt lake brine at a rate of 1mL/min to 5 mL/min.